Discharge lamp



March 29, 1960 w, WAINIQ ETAL DISCHARGE LAMP 2 Sheets-Sheet 1 Filed Feb.12, 1958 4.5. .St/PPA) w mm EM M m m a W H n M m March 29, 1960 A. w.WAINIO ET 2,930,934

DISCHARGE LAMP Filed Feb. 12, 1958 2 Sheets-Sheet 2 /b ll I a UnitedStates Patent '0 DISCHARGE LAMP Albert W. Wainio, Pompton Plains, andThomas H. Heine, Cedar Grove, N.J., assignors to Westinghouse ElectricCorporation, East Pittsburgh, Pa., a corporation of PennsylvaniaApplication February 12, 1958, Serial No. 714,874

7 Claims. (Cl. 315-46) This invention relates to discharge devices and,more particularly, to self-starting, low-pressure, positive-columndischarge devices.

Fluorescent lamps are very widely used because of their high operatingefliciency and long life. The use of such lamps, however, has beensomewhat limited because of the relatively expensive ballast andstarting equipment which is required to operate these lamps. Thestarting and ballasting arrangements have taken various forms, but allare similar in that some transformer means is utilized to increaseconsiderably the voltage applied between the lamp electrodes duringstarting in order to ionize the discharge path which is defined by thelamp electrodes. Various means have been suggested for startingfluorescent lamps, for example such as disclosed in Patent No. 2,097,261to Spanner. In addition, various electrode arrangements for facilitatingstarting of such lamps have been disclosed, for example such asdescribed in Patent No. 2,733,371 to Campbell. None of the foregoing orother previously-suggested arrangements for starting fluorescent lampshave ever been practical for starting on a voltage even approaching thelamp operating voltage or the line voltage. Also, where fluorescentlamps are designed to have so-called instantor rapidstartcharacteristics, the starting and ballast arrangements become even moreexpensive. Accordingly, commercially-available fluorescent lamps allrequire the use of fairly elaborate starting arrangements.

It is the general object of the present invention to avoid and overcomethe foregoing and other difiiculties of and objections to the prior artby providing a self-starting fluorescent lamp which will immediatelystart on line voltage without the use of auxiliary voltage-boostingequipment.

It is a further object to provide a self-starting fluorescent lamp whichwill immediately start with considerably less than the usual startingvoltage required; It is an additional object to provide a self-startingfluorescent lamp which will immediately start with an applied voltagewhich is only slightly greater than the initial lamp-operating voltage;

It is another object to provide various modifications for suchself-starting fluorescent lamps.

The aforesaid objects of the invention, and other objects which willbecome apparent as the description proceeds, are achieved by providing aself-starting, positivecolumn, electric-discharge device wherein atleast one pair of thermionic auxiliary starting electrode coils areprovided at predetermined locations within the lamp envelope and arespaced apart a predetermined distance. These auxiliary startingelectrode coils have such configuration and resistance that less currentis required to cause them to become thermionically emissive than thethermionic main electrode coils which are provided for the lampoperation. At least one pair of the auxiliary starting electrode coilsare connected by a starting resistor whose resistance is preselectedaccording to the re sistances of the electrode coils of the lamp, thespacing between the electrode coils'and the potential at which the For abetter understanding of the invention, reference should be had to. theaccompanying drawings wherein: 'Fig. 1' is an elevational view, partlyin section, of a fluorescent lamp constructed in accordancewith theinstant teachings, including current-limiting ballast resistors; Fig. 2is a diagrammatic view of the electrode and self-starting circuitryarrangement for the lamp as shown in Fig. 1, including additional leadconductors which may be provided to treat the lamp electrodes;

Fig. 3 is a sectional view taken on the line III-III in Fig. l;

Fig. 4 is an alternative embodiment of a portion of the lamp as shown inFig. 1, wherein the ballast resistance is included as an integral partof the lamp;

Fig. 5 is a diagrammatic view of an alternative embodiment for theself-starting lamp as disclosed in Fig. 2, wherein additional resistorelements are provided between the auxiliary starting electrode coils andthe main electrode coils;

Fig. 6 is a diagrammatic view of another embodiment corresponding toFig. 5, but showing the auxiliary starting electrode coils spacedconsiderably apart from the main electrode coils; v

Fig. 7 is a diagrammatic view of still another embodiment showing theauxiliary starting electrode coils spaced considerably apart from themain electrode coils, but wherein only one series-connected startingresistor is utilized; l v

Fig. 8 is a diagrammatic view of a further alternative embodimentwherein two pairs of starting electrode coils are utilized, withauxiliary starting resistors included between each of theseries-connected electrode coils;

Fig. 9 is a diagrammatic view of another embodiment corresponding toFig. 8, but wherein one pair of auxiliary starting electrode coils areplaced proximate the operating electrode coils of the lamp, and theauxiliary starting resistors between the proximate starting electrodecoils and operating electrode coils are eliminated;

Fig. 10 is a diagrammatic view of yet another embodiment illustrating a.high-loaded fluorescent lamp wherein two pairs of auxiliary startingelectrode coils are positioned near the operating electrode coils of thelamp, with the innermost pair of auxiliary starting electrode coilsconnected by a starting resistor.

With specific reference to the form of the invention illustrated in thedrawings, in Figs. 1, 2 and 3 are shown a self-starting,positive-column, electric-discharge lamp 10 which generally comprises avitreous, light-transmitting, elongated envelope 12, containing a lowpressure of inert, ionizable gas and a small charge, of mercury 14, asis usual. The inert ionizable gas may comprise argon at a pressure offour millimeters, for example, and in the case of a twenty-watt lamphaving an envelope diameter of one and one-half inches, the mercurycharge may be in the order of forty milligrams. Starting gases otherthan argon may be utilized, as is well known. Also, the starting gaspressure may be varied over wide limits and is not critical. Likewise,the charge of mercury 14 may be varied considerably, as is well known.

A coating of phosphor material 16 is normally coated on the interiorsurface of the lamp envelope 12, Which phosphor material is excitable bythe 2537' AU, rad i ations which are generated by the mercury dischargein order to convert these ultraviolet radiations into visible light.Such phosphor materials are well known and as an example,- a zincsilicate phosphor may be utilized. If desired, the lamp envelope neednot include the phosphor coating'and such a construction may be utilizedwith bactericidal types of lamps which may be provided with an envelopewhich is transmissive to the 2537 AU. radiations.

Operatively disposed proximate either end of the envelope 12 are a pairof main electrode coils 18, each of which may be formed a. refractorymetal such as 1.4 mil tungsten wire, for example, and which coilsdesirably have the configuration of a coiled-coil, with the turns ofeach inner coil filled with electron-emissive material such as bariumoxide or a mixture of alkaline-earth oxides. Other additive materialsmay be included with the alkaline-earth oxides, such as a small amountof zirconia, for example. Electron-emissive materials other than thealkaline-earth oxides may be used to activate the electrode coils inorder to render them thermionically emissive and such otherelectron-emissive materials are well known.

As disclosed in Figs. 1 and 2, a pair of thermionic starting electrodecoils 20 are connected in series with the main operating electrode coils18 and are positioned proximate thereto with a spacing therebetween ofone inch, for example. This spacing may be increased or decreased, ifdesired. The starting electrode coils 20 may also be fabricated of arefractory material such as 1.0 mil tungsten wire and desirably areprovided with a coiledcoil configuration and, as in the case of the mainelectrode coils, are activated with electron-emissive material.

Lead-in conductors 22 are sealed through the lamp envelope 12 and areelectrically connected to one side of each of the main electrode coils18 in order to supply electrical power thereto and the startingelectrode coils 20 are electrically connected to the other coil sides ofthe main electrode coils. Connected between the other coil sides of thestarting electrode coils 20 is an elongated resistor element 24 which ispreferably coiled and under tension in order to facilitate lampfabrication and in order that the resistor element 24 is alwaysmaintained apart from the phosphor coating 16, as shown in Pig. 3. Theresistor element 24 may be fabricated of Nichrome alloy, such aschromium, 61% nickel and 24% iron, for example. Nichrome is a trademarkof Driver- Harris Co., Harrison, N].

If the lamp main and starting electrode coils 18 and are activated withalkaline-earth-oxide materials, such materials are normally applied tothe refractory electrode coils as alkaline-earth carbonates and it isnecessary to treat these carbonates with heat in order to break themdown to the thermionic oxides. Such electrode-treatment is facilitatedby two additional conductors 26 which also serve to support theelectrode coils and one each of which additional conductors areconnected intermediate each of the starting and main electrode coils. Insuch electrode treating, a potential may be applied across each of thelead-in conductors 22 and additional conductors 26 in order to treat themain electrode coils 18, and an additional potential may be appliedacross the additional conductors 26 in order to treat the startingelectrode coils 20. Such electrode treating procedures may proceedsimultaneously in order to facilitate speed of lamp manufacturing.Alternatively, electrode treating could be accomplished by inductionheating.

After electrode treating the envelope is provided with the proper gasfill and mercury charge, the outwardlyextending ends of the additionallead conductors 26 are cut off and base caps 28 are secured to the endsof the lamp envelope 12. In the instant lamps, only one electricalconnection is required at each end of the envelope 12 and this isprovided by base contacts 30 which are electrically connected to thelead conductors 22. The finished lamps incorporating the alternativeembodiments shown in diagrammatic form in Figs. 5 through 10 maycorrespond to the lamp as shown in Fig. 1, with respect to the baseconnections.

The starting electrode coils 20 are each supported by a lead conductorand insulating head support, wherein two lead conductors 32 and 34,which support a starting electrode coil 20 between their ends, areretained in spaced relationship by an insulating glass head 36. One ofthe lead conductors 34 is supported by one of the additional treatingand support conductors 26 and the other lead conductor 32 connects tothe starting resistor 24. Cther modifications for supporting thestarting electrode coils 20 are also possible, but the foregoing supportarrangement is quite simple and easily fabricated.

The resistance and the configuration of the starting electrode coils 20and the main electrode coils 18 are so selected that less current isrequired to cause the starting coils 20 to become thermionicallyemissive than the main electrode coils 18. Also, the preselectedresistances and configurations of the electrode coils are also dependentupon the voltage which will be utilized to start and operate the lampand the spacing between the starting electrode coils, as well as theresistance of the starting resistor 24. As a specific example, with aspacing between the starting electrode coils of twenty-four inches, eachstarting electrode coil 20 may have a hot resistance of 285 ohms (coldresistance 57 ohms), each main electrode coil may have a hot resistanceof 50 ohms (cold resistance 10 ohms) and the Nichrome alloy startingresistor may have a hot or cold resistance of 900 ohms. Each startingcoil may carry 1.2 milligrams of electron-emissive material comprising56% by weight barium oxide, 13% calcium oxide and 31% strontium oxideand each main coil may carry 5 milligrams of similar electron-emissivematerial.

The usual fluorescent lamp operates with what is known as anegative-volt-ampere characteristic. That is, the greater the currentthrough the lamp, the lower the resistance of the electric discharge.Without some additional ballasting resistor or reactance, this wouldresult a runaway discharge which would destroy the lamp. The instantself-starting lamps are no different from the usual fluorescent lamp inthis respect, and additional ballasting impedances 38 may be provided inseries with one or with both of the lead conductors 22, as shown inFig. 1. Such ballasting impedances may be provided external to the lampor they may be built within the lamp base or envelope as shown in Fig. 4wherein the ballast resistance 38a is contained within an elongatedflare tube 39. While in the embodiments as disclosed, the ballastingimpedances have taken the form of resistors, suitable reactances couldbe utilized, as is well known.

In the operation of the lamp as disclosed in Figs. 1 and 2, if volts isapplied across the ballast resistors and lamp, a current will fiowthrough the series circuit which is formed by the main electrode coils18, the starting electrode coils 20 and the starting resistor 24. Forthe specified embodiment, the ballast resistors 38 may be so selectedthat the voltage which is applied between the main electrode coils 18will be approximately 102 volts. This will cause a current of 0.065ampere to be drawn by the series circuit, with 95.5 volts potential lropoccurring across the starting coils and the starting resistor 24. Thisindicated series current will cause the starting electrode coils 20 tobecome thermionically missive and the total potential drop between thestarting electrode coils will cause an electric discharge to beestablished between these starting electrode coils 20. Since theelectric discharge which occurs from starting coil to starting coil hasa much lower resistance than the resistor element 24 and those portionsof the starting coils 2-3 which are shorted out by the discharge, aheavier current such as 0.25 ampere, for example, will be drawn by thelamp. This increased current will cause the main electrode coils 18 tobecome thermionically emissive. In addition, the increased current willcause an increased potential drop across the main electrode coils sothat the maximum potential drop between these coils, after the initialdischarge between the starting coils 20 has been established, will beabout 95 volts, for example. The increased electron emissivity of themain electrode coils 18 and the increased potential drop therebetweenwill cause an electric discharge to be established between these mainelectrode coils. The series circuit which was utilized to start the lampwill continue to draw some current, but since the discharge which occursbetween the main electrode coils 18 has a much lower resistance than theseries circuit included between the hot spot or operating portion of themain electrode coils, the power loss will be relatively small. As anexample, for the, embodiment as described 91 percent of the totalcurrent drawn by the lamp will traverse the discharge path between themain electrode coils 18.

If the path between the auxiliary starting electrode coils 20 isshortened to 16 inches, for example, the components comprising theseries circuit utilized to start the lamp are desirably varied somewhat.As an example, for 110 volt operation, the resistance of the startingcoils may be such that when a current of 0.065 ampere is drawn by theseries circuit during starting, a potential drop of 18.5 volts willoccur across these starting coils and a potential drop of 33.6 voltsacross the shorter starting resistor will be satisfactory to start thelamp. Thus the resistance and configuration of the starting coils andthe main electrode coils as well as the resistance and length of theprimary resistor element are preselected in accordance with the lampdesign and the voltage under which the lamp is designed to start andoperate. All of the foregoing are readily determinable for each specificlamp design.

In Fig. 5 is shown an alternative embodiment of the lamp as illustratedin Fig. 2, wherein additional resistor elements 40 are included betweeneach of the auxiliary starting coils 20 and the main coils 13a. In suchan embodiment, the starting coils 20 may be proximate the main coils,the spacing between the starting coils may be 24 inches, for example,and the resistors 40, which may be Nichrome alloy, may each have a hotor cold resistance of 150 ohms. This enables the main coils 18a to befabricated from 2.3 mil tungsten wire, for example, with slightly-lower,hot electrical resistance, such as 11.75 ohms. The other componentscomprising the series circuit may be the same as in the embodiment shownin Fig. 2. Such a construction assists in assuring positive startingthroughout the life of the lamp.

In Fig. 6 is illustrated a further embodiment of the lamp as shown inFig. 2, wherein the starting coils 20 are spaced in predeterminedlocations within the envelope and are spaced apart from the main coils18a. Also, the additional resistor elements 40 are included in theseries circuit between each of the starting coils 20 and the main coils18a. The components which comprise the series circuit may be asdescribed for the embodiment as shown in Fig. 5 except that the spacingbetween each of the starting coils 20 and the nearest operating coil 18amay be eight inches, for example. The starting electrode coils 20 may besupported with a lead conductor and insulating head support, asdescribed previously for the embodiment shown in Fig. 1, and additionalinsulating members 42, such as glass members, may be used to providesupport between the supporting conductors 26 and the supports for thestarting electrode coils 20. If desired, the additional startingresistors 40 may be wrapped around the insulating support members 42 inorder to facilitate fabrication. While other supporting arrangements forthe starting electrode coils 20 and starting resistor 24 may beutilized, the foregoing arrangement has been found to be verysatisfactory.

In the embodiment as shown in Fig. 7, the additional startingresistorsAQ have been eliminated and the voltage dropwhich occurs acrossthe main electrode coils 18 b, after the electric discharge has beenestablished between the starting electrodejcoils 20, is sufiicient tocause the discharge to be established between the main electrode coils18b. In such an embodiment, the main electrode coils 18b may befabricated of 1.4 mil tungsten wire, for example, with a hot electricalresistance of ohms and the starting electrode coils 20 as well as thestarting resistor 24 may be as described in the embodiment shown in Fig.2. The spacing between the starting electrode coils 20 may betwenty-four inches and the spacing between each of the startingelectrode coils 20 and the nearest main electrode coil 18b may be eightinches, for example. i

In Fig. 8 is shown another embodiment which enables a still-longer lampto be started with a much-lower voltage than 'is normally required tostart a lamp of such length dimensions. In this embodiment, the twocentrallydisposed primary starting electrode coils 20 may have a spacingtherebetween of twenty-seven inches and these primary starting electrodecoils may be as described in the embodiment shown in Fig. 2. The firststarting resistor 2411 may be fabricated of Nichrome alloy with aresistance of 1864 ohms. The series circuit, which includes the startingelectrode coils 20 and first starting resistor 24a, also includes twosecondary starting electrode coils 44. These are positioned within theenvelope in predetermined locations intermediate the main operatingcoils 18c and the primary pair of starting electrode coils 20 and eachmay be fabricated of 2.3 mil tungsten wire with a hot resistance of 11ohms and a cold resistance of 2.2 ohms. The main operating coils may befabricated of 5.0 mil tungsten wire with a hot resistance of three ohms,for example, and are desirably positioned proximate either end of theenvelope. Connecting the primary starting coils 20 and the secondarystarting coils 44 are second resistor elements 46, each of which may befabricated of Nichrome alloy, for example, and may have a hot or coldresistance of 67 ohms. Connecting the secondary starting coils 44 andthe operating coils 180 are third resistor elements 48, each of whichmay be fabricated of Nichrome alloy, for example, with a hot or coldresistance of 27 ohms. Such a lamp also includes a ballasting resistorarrangement (not shown), as in the embodiment illustrated in Figs. 2 or4, although because of the increased current such a lamp will draw, thetotal ballasting resistance need only by 60 ohms, for example. As noted,the primary starting coils may be spaced twentyseven inches apart andeach of the secondary and operating coils may be positioned ten andtwenty inches, respectively, from the nearest primary starting coil 20to form a 72Tl2-type lamp.

The resistance and configuration of the primary and secondary startingcoils 20 and 44 and the operating coils 180 is so selected that lesscurrent is required to cause the secondary starting coils 44 to becomethermionically emissive than the operating coils 18c and more current isrequired to cause the secondary starting coils 44 to becomethermionically emissive than the primary starting coils '20. Theresistance of the primary or first resistor element 24:: and that of thesecond and third resistor elements 46 and 48 is preselected according tothe resistance of the electrode coils within the lamp and the spacingbetween these electrode coils, with the resistance I in Fig. 8, when apotential such as 176 volts, for example,

is applied across the ballast and series-starting circuit, the seriescircuit draws a current of .065 ampere, for example, which causes theprimary starting coils 20 to become thermionically emissive. This, whencoupled with the potential drop between the primary starting coils 20,causes an electric discharge to be established therebetween. Since theresistance of the electric discharge formed between these primarystarting coils 20 is considerably less than the resistance of theparalleling starting resistor 24a and the portions of the primarystarting coils which are shorted out by the discharge, an increasedcurrent will be drawn by the lamp and this will increase the potentialdrop across the second starting resistors 46 and will also increase thepotential drop between the secondary starting coils 44. This in turnwill cause an electric discharge to be established between the secondarystarting coils 44 which will in turn increase the current through themain operating electrode coils 18c and third resistor elements 48. Thisincreased current will cause the main operating electrodes 18c to becomethermionically emissive and the increased potential drop between theoperating electrode coils 180 will cause an electric discharge to beestablished therebetween. With such an arrangement, a lamp having alength'of 72 inches, for example, may readily be started and operatedwith 176 volts. This is to be contrasted with the 525 volts usuallyrequired to start such a lamp or with the 250 volts required if externalpreheat is provided.

If desired, the third resistor elements 48 may be eliminated from thecircuit and the secondary starting coils 44 may be placed proximate theoperating coils 18d as shown in Fig. 9. In such an embodiment, all ofthe corresponding components may be the same as for the embodiment shownin Fig. 8, except that the first starting resistor 24 may be asdescribed for the embodiment as shown in Fig. 2 and the main operatingcoils 18d may each befabricated from 5.0 mil tungsten wire with a hotelectrical resistance of 12 ohms, for example, and a total distancetherebetween of 47 inches.

'In the usual fluorescent lamp, the current drawn by the lamp, whichrepresents the lamp loading, is relatively small so that the mercurydischarge will operate with a maximum of efliciency in generating 2537AU. radiations. As an example, the usual 40 watt T12-type of lamp drawsa current of about 0.430 ampere. In some types of fluorescent lamps, theballast impedance is decreased so that the lamp will draw a much-heaviercurrent in order that the power consumption of the lamp is increased toincrease the light output. Such lamps may be termed high-loadedfluorescent lamps. With such high-loaded fluorescent lamps, themercury-vapor pressure may be controlled by special envelopeconfigurations or by the provision of cool ends within the envelope sothat the efficiency of the discharge is not decreased appreciably by theincreased loading. The operating electrode coils for such highloadedfluorescent lamps necessarily have a relatively small resistance. Thuswhere the instant self-starting designs are utilized with highloadedfluorescent lamps, the current drawn by the series starting circuit andthe current drawn by the lamp after the initial discharge between theprimary starting electrode coils has been established may not besuflicient to cause the operating electrode coils of the lamp to becomesufiiciently thermionically emissive to establish the operatingdischarge therebetween.

In Fig. 10 is shown an embodiment wherein a highloaded fluorescent lamphas been adapted for self-starting in accordance with the instantteachings, which lamp is designed to operate with a low-impedance chokeballast. In the embodiment as illustrated, heat-reflector shields 50 areprovided at either end of the lamp envelope 12 in order to make thelamp-envelope ends operate relatively cool to limit the mercury-vaporpressure in order to maintain an efiicient discharge. Such designs arewell known. The operating electrode coils 18e are spaced interiorly ofand proximate the heat-reflector shields 5t) and each may comprise a 5.0mil wire tungsten coiledcoil or triple-wound coil, for example, coatedwith 20 milligrams of alkaline-earth, electron-emissive material asspecified hereinbefore. Positioned interiorly of the operating electrodecoils 182 are a pair of primary starting electrode coils 20 connected bya starting resistor 24. The construction and spacing for these primarystarting electrode coils 20 and starting resistor 24 may be as describedfor the embodiment shown in Fig. 2. As noted, the operating electrodecoils 18e for this highloaded fluorescent lamp are designed to carryheavy currents and each may have a hot resistance of 18 ohms and a coldresistance of 3.6 ohms. In such an embodiment, the current drawn by thelamp after the discharge has been initiated between the primary startingelectrode coils 20 will be relatively small, such as 0.360 ampere, andthis may be insuflicient to cause the operating electrode coils 18e tobecome sufiiciently thermionically emissive to enable the main dischargeto be established. In order to enable such a high-loaded fluorescentlamp to be started with the instant design, it is desirable to include asecondary pair of starting electrode coils 44a between the operatingelectrode coils 182 and primary starting electrode coils 20. Suchsecondary pair of starting electrode coils may each be formed of 2.3 miltungsten wire with a coiled-coil configuration and be coated withalkaline-earth oxides as specified hereinbefore. The hot resistance ofeach of these electrode coils 44:: may be 50 ohms and the coldresistance may be 10 ohms. The current lead-ins 22, the operatingelectrode coils 13c, starting electrode coils 20 and 44a and startingresistor 24 are all connected to form a series circuit as in theprevious embodiments. As a specific example, the spacing between theprimary starting electrode coils 20 may be twenty-four inches, thespacing between each of the operating electrode coils ISe and thenearest primary starting electrode coil 20 may be eight inches and eachof the secondary starting electrode coils 44a may be positionedintermediate therebetween. In the operation of this embodiment, when thestarting potential such as 105 volts is applied across the lamp, adischarge will be initiated between the primary starting electrode coils20 which will cause the lamp to draw a current of 0.360 ampere.Immediately thereafter, the discharge will be initiated between thesecondary starting electrode coils 44a which will cause the lamp to drawa current of 1.0 ampere. Immediately thereafter, the discharge will beestablished between the operating electrode coils 18c which will causethe lamp to draw a current of 1.3 atnperes, for example. The instantstarting design operates very efficiently with such a lamp design asshown in Fig. 10, since the series circuit which is formed by electrodecoils and starting-resistor arrangement has a much higher resistancethan the main discharge. As an example, for the embodiment described inFig. 10, 96 percent of the total current drawn by the lamp will traversethe discharge path between the operating electrode coils and will beetfective in generating ultraviolet radiations. The so-calledhigh-loaded fluorescent lamps operate on a relatively low voltagebecause of the comparatively heavy current which such lamps draw.However, the initial operating voltage, before the lamp has fully warmedup, is relatively high and for the specific example described may bevolts. In the instant design, the lamp starting voltage will be onlyslightly greater than the initial lamp-operating voltage. It should benoted that electrode treating for the embodiments as shown in Figs. 8through 10 may be accomplished by induction heating, for example.

In the operation of the embodiments shown in Figs. 8 through 10, theinitial discharge is established between the primary starting electrodecoils and thereafter progresses to the operating electrode coils via thesecondary starting electrode coils. These progressive discharges whichoccur during lamp starting progress very rapidly and the main dischargeis established almost immediately upon application of the potentialacross the lamp.

Still-further embodiments are possible. For example,

the third resistor elements 48 as shown in Fig. 8 could be includedbetween the secondary starting electrode coils 44 when such coils arepositioned proximate the operating electrode coils, as shown in Fig. 9.Also, it may be desirable to provide additional support members for thecomponents comprising the series starting circuit for the embodiments asshown in Figs. 8 through 10, although an insulating-bead-supportarrangement as shown in Fig. 1 may be used.

It will be recognized that the objects of the invention have beenachieved by providing a self-starting fluorescent lamp which willimmediately start on line voltage without the use of auxiliaryvoltage-boosting equipment. In addition there have been providedself-starting fluorescent lamps which will immediately start withconsiderably less than the usual starting voltage required and whichwill immediately start with an applied voltage only slightly greaterthan the initial lamp-operating voltage. Also, there have been providedvarious alternative embodiments for such self-starting fluorescentlamps.

While best-known embodiments have been illustrated and described indetail, it is to be particularly understood that the invention is notlimited thereto or thereby.

We claim:

1. A self-starting, positive-column, electric-discharge devicecomprising: a light-transmitting, elongated envelope containing a lowpressure of inert, ionizable gas and a small charge of mercury; a pairof thermionic main electrode coils, activated with electron-emissivematerial, operatively disposed proximate either end of said envelope;lead-in conductors sealed through said envelope and connecting to saidmain electrode coils; a pair of thermionic starting electrode coils,activated with electron-emissive material, spaced apart a predetermineddistance and positioned in predetermined locations within said envelope;the resistance and configuration of said starting coils and said mainelectrode coils being so selected that less current is required to causesaid starting coils to become thermionically emissive than said mainelectrode coils; a primary nonthermionic resistor element within saidenvelope and connecting said starting coils; additional nonthermionicresistor elements within said envelope and connecting said startingcoils and said main electrode coils; the resistance of said primaryresistor element and said additional resistor elements being preselectedaccording to the resistance of said electrode coils and the spacingbetween said starting electrode coils, with said primary resistorelement having a substantially higher resistance than either of saidadditional resistor elements; a series circuit formed by said lead-inconductors, said starting coils, said main coils and said connectingresistor elements; upon application of a predetermined potential acrosssaid lead conductors, said starting coils becoming thermionicallyemissive with the potential drop across said starting coils and saidprimary resistor element causing an electric discharge to be establishedbetween said starting coils resulting in an increased current throughsaid main electrode coils and said additional resistor elements, theresulting increased current through said main electrode coils causingsame to become,

thermionically emissive with the increased potential drop across saidmain electrode coils and said additional resistor elements causing anelectric discharge to be established between said main electrode coils.

2. A self-starting, positive-column, electric discharge devicecomprising: a light-transmitting, elongated envelope containing a lowpressure of inert, ionizable gas and a small charge of mercury; a pairof thermionic main electrode coils, activated with electron-emissivematerial, operatively disposed proximate either end of said en velope;lead-in conductors sealed through said envelope and connecting to saidmain electrode coils; a pair of thermionic starting electrode coils,activated with electron-emissive material, spaced apart a predetermineddistance intermediate said main electrode coils and positioned inpredetermined locations within said envelope; the resistance andconfiguration of said starting coils and said main electrode coils beingso selected that less current is required to cause said starting coilsto become thermionically emissive than said main electrode coils; aprimary nonthermionic resistor element within said envelope andconnecting said starting coils; additional nonthermionic resistorelements within said envelope and connecting said starting coils andsaid main electrode coils; the resistance of said primary resistorelement and said additional resistor elements being preselectedaccording to the resistance of said electrode coils and the spacingbetween said starting electrode coils, with said primary resistorelement having a substantially higher resistance than either of saidadditional resistor elements; a series circuit formed by said lead-inconductors, said starting coils, said maincoils and said connectingresistor elements; upon application .of a predetermined potential acrosssaid lead conductors, said startingcoils becoming thermionicallyemissive with the potential drop across said starting coils and saidprimary resistor element causing an electric discharge to be establishedbetween said starting coils resulting in an increased current throughsaid main electrode coils and said additional resistor elements, theresulting increased current through said 'main electrode coils causingsame to become thermionically emissive with the increased potential dropacross said main electrode coils and said additional resistor elementscausing an electric discharge to be established between said mainelectrode coils.

3. A self-starting, positive-column, electric-discharge devicecomprising: a light-transmitting, elongated envelope containing a lowpressure of inert, ionizable gas and a small charge of mercury; a pairof thermionic main electrode coils, activated with electron-emissivematerial, operatively disposed proximate either end of said envelope;lead-in conductors sealed through said envelope and connecting to saidmain electrode coils; a pair of thermionic starting electrode coils,activated with electron-emissive material, spaced apart a predetermineddis-' tance within said envelope and positioned proximate said mainelectrode coils; the resistance and configuration of said starting coilsand said main electrode coils being so selected that less current isrequired to cause said starting coils to become thermionically emissivethan said main electrode coils; a primary nonthermionic resistor elementwithin said envelope and connecting said starting coils; the resistanceof said primary resistor element being preselected according to theresistance of said electrode coils and the spacing between said startingelectrode coils; a series circuit formed by said leadin conductors,saidstarting coils, said main-coils and said connecting resistorelement; upon application ,of a predetermined potential across said leadconductors, said starting coils becoming thermionically emissive withthe potential drop across said starting coils and'said primary resistorelement causing an electric discharge to be established between saidstarting coils resulting in an increased current through said mainelectrode coils, the resulting increased current through said mainelectrode coils causing same to become thermionically emissive with theincreased potential drop therebetween causing an electric discharge tobe established between said main electrode coils. I

' 4. A self-starting, positive-column, electric-discharge device.comprising: a light-transmitting, elongated envelope containing a lowpressure of inert, ionizable gas and a small charge of mercury; a pairof thermionic main electrode coils, activated with electron-emissivematerial, operatively disposed'proximate either end of said envelope;lead-in conductors sealed through said envelope,

sass-3'4 and connecting to said main electrode coils; a pair ofthermionic Starting electrode coils, activated with electron-emissivematerial,.spaced apart a predetermined distance and positioned inpredetermined locations within said envelope; the resistance andconfiguration of said starting coils and said main electrode coils beingso selected that less current is required to cause said starting coilsto become thermionically emissive than, said main electrode coils; aprimary nonthermionic resistor element within said envelope andconnecting said starting coils; the resistance of said primary resistorelement being preselected according to the resistance of said electrodecoils and the spacing between said starting electrodecoils; a seriescircuit formed by said lead-in conductors, said starting coils, saidmain coilsrand said connecting re sistor element; additional electrodetreating lead-in conductors sealed through said envelope andrespectively electrically connected between said main electrode coilsand said starting coils; upon application of a predetermined potentialacross said lead conductors, said starting coils becoming thermionicallyemissive with the potential drop across said starting coils and saidprimary resistor element causing an electric discharge to be establishedbetween said starting coils resulting in an increased current throughsaid main electrode coils, the resulting increased current through saidmain electrode coils causing same to become thermionically emissive withthe increased potential drop therebetween causing an electric dischargeto be established between said main electrode coils.

5. A self-starting, positive column, electric-discharge devicecomprising: a light-transmitting, elongated envelope containing a lowpressure of inert, ionizable gas and a small charge of mercury; a pairof thermionic operating electrode coils, activated withelectron-emissive material, operatively disposed proximate either end ofsaid envelope; lead-in conductors sealed through said envelope andelectrically connecting to said operating coils; a primary pair ofstarting electrode coils, activated with electron-emissive material,positioned within said envelope in predetermined locations intermediatesaid operating coils and spaced apart from one another a predetermineddistance; a secondary pair ofrstarting electrode coils, activated withelectron-emission material, respectively spaced in predeterminedlocations on either side of and further apart than said primary startingcoils; the resistance and configuration of said primary andsaidsecondary starting coils and said operating coils being so selected thatless current is required to cause said secondarystarting coils to becomethermionically emissive than said operating 'coils and more current isrequired to cause said secondary starting coils to become thermionicallyemissive than said primary starting coils; a first nonthermionicresistor element within said envelope and connecting said primarystarting coils; second nontherinionic resistor elements within saidenvelope and connecting said primary starting coils and said secondarystarting coils; third nonthermionic resistor elements Within, said en'-velope and connecting said secondary starting coils and said operatingcoils; the resistance of said first resistor element and said second andthirdresistor elements being preselected according to the resistance ofsaidelectrode coils and the spacing between said electrode coils, withthe resistance of each of said second resistor elements being less thanthe resistance of said first resistor element and greater than theresistance of each of said third resistor elements; a series circuitformed by said current lead-ins and said electrode coils and theresistor elements connecting therebetween; upon application of apreselected'potential across said current lead-ins, said primarystarting coils becoming thermionically emissive with the potential dropacross said primary starting coils and said first resistor elementcausing an electric discharge to be established between said primarystarting coils resulting in an increased current through said secondarystarting coilsand saidseco'rid resistor elements, the resulting increased current through said secondary starting coils causing sametobecome thermionically emissive with the increased potential drop acrosssaid secondary starting coils and said second resistor elements causingan electric discharge to be established between said secondary startingcoils to increase the current through said operating coils and saidthird resistor elements, the increased current through said operatingcoils causing same to become thermionically emissive with the increasedpotential drop across said operating coils and said third resistorelements causing an electric discharge to be established between saidoperating coils.

6. A self-starting, positive column, electric-discharge devicecomprising: a light-transmitting, elongated envelope containing a lowpressure of inert, ionizable gas and a small charge of mercur; a pair ofthermionic operating electrode coils, activated with electron-emissivematerial, operatively disposed proximate either end of said envelope;lead-in conductors sealed through said envelope and electricallyconnecting to said operating coils; a primary pairof starting electrodecoils, activated with electron-emissive material, positioned within saidenvelope in predetermined locations intermediate said operating coilsand spaced apart from one another a predetermined distance; a secondarypair of starting electrode coils, activated with electron-emissivematerial, respectively spaced in predetermined locations on either sideof and further apart than said primary starting coils; the resistanceand configuration of said primary and said secondary starting coils andsaid operating coils being so selected that less current is required tocause said secondary starting coils to become thermionically emissivethan said operating coils and more current is required to cause saidsecondary starting coils to become thermionically emissive than saidprimary starting coils; a first nonthermionic resistor element withinsaid envelope and connecting said primary starting coils; secondnonthermionic resistor elements Within said envelope and connecting saidprimary starting coils and said secondary starting coils; the resistanceof said first resistor element and said second resistor elements beingpreselected according to the resistance of said electrode coils and thespacing between said starting electrode coils, with the resistance ofeach'of said second resistor elements being less than the resistance ofsaid first resistor element; a series circuit formed by said currentlead-ins and said electrode coils and the resistor elements connectingtherebetween; upon application of a preselected potential across saidcurrent lead-ins, said primary starting coils becoming thermionicallyemissive with the potential drop across said primary starting coils andsaid first resistorelement causing an electric discharge to beestablished between said primary starting coils resulting in anincreased current through said secondary starting coils' and said secondresistor elements, the resulting increased current through saidsecondary starting coils causing some to become thermionically emissivewith the increased potential drop across said secondary startingcoils'and said second resistor elements causing an electric discharge tobe established between'said secondary starting coils to increase thecurrent through said operating coils, the increased current through saidoperating coils causing same to become thermionically emissive with theincreased potential drop therebetween causing an electric discharge tobe established between said operating coils.

7. A'self-starting, positive column, electric-discharge devicecomprising: a light-transmitting, elongated envelope containing a lowpressure of inert, ionizable gas and a small charge of mercury; a pairof thermionic operating electrode coils, activated withelectron-emissive material,'operatively disposed proximate either end ofsaid envelope; lead-in conductors sealed through said envelope andelectrically connecting to said operating coils; a primary pair' ofstarting electrode coils, activated with electron-emissivematerial,positioned within saiden- 13 velope in predetermined locationsintermediate said operating coils and spaced apart from one another apredetermined distance; a secondary pair of starting electrode coils,activated with electron-emission material, respectively spaced inpredetermined locations on either side of and further apart than saidprimary starting coils;

the resistance and configuration of said primary and said secondarystarting coils and said operating coils being so selected that lesscurrent is required to cause said secondary starting coils to becomethermionically emissive than said operating coils and more current isrequired to cause said secondary starting coils to become thermionicallyemissive than said primary starting'coils; a first nonthermionicresistor element connecting said primary starting coils; the resistanceof said first resistor element being preselected according to theresistance of said electrode coils and the spacing between said primarystarting electrode coils; a series circuit formed by said currentlead-ins and said electrode coils and the resistor element connectingbetween said primary starting coils; upon application of a preselectedpotential across said current lead-ins, said primary starting coilsbecoming thermionically emissive with the potential drop across saidprimary starting coils and said first resistor element causing anelectric discharge to be established between a is said primary startingcoils resulting in an increased currentthrough said secondary startingcoils, the resulting increased current through said secondary startingcoils causing same to become thermionically emissive with the increasedpotential drop therebetween causing an electric discharge to beestablished between said secondary starting coils to increase thecurrent through saidoperating coils, the increased current through saidoperating coils causing same to become thermionically eniissive with theincreased potential drop therebetween causing an electric discharge tobe established between said operating coils. 1 References Cited in thefile of this patent V UNITED STATES PATENTS 1,860,210 Spanner et a1. May24, 1932 1,925,648 Spanner et a1. Sept. 5, 1933 2,085,561 Wiegand June29, 1937 2,097,261 Spanner Oct. 26, 1937 2,189,508 Macksoud Feb. 6, 19402,246,339 Beregh June 17, 1941 2,291,926 Sperti Aug. 4, 1942 2,304,768Lederer Dec. 8, 1942 Smith July 16, 1946

